My wrap-up column for the year concerns the single event that dominates all others: the mass murder at Sandy Hook Elementary School in Newtown.

I grew up with guns. On the farm, there were rifles tucked in the corner of the entry hall. They were there to kill varmints and occasionally hunt deer, and as a legacy of American settlement history. They were used like pitchforks or axes, as tools to get some job done. Though any could have been used violently, none were. Hard work, family honor and having integrity made the man. Not the length of his gun barrel, its bore, or its potency.

In the town of my youth, sport hunting was a routine part of life, more visible than professional basketball. Churches sponsored hunters' breakfasts cooked by tenderhearted women and served by youth groups.

Violence toward humans is a separate issue. It's an unavoidable part of life, present since Day One in every type of history: evolutionary, archaeological and recorded. Luckily, it's been diminishing as civilization progresses, at least according to renowned psychologist Stephen Pinker. The task of every humane person is to keep this trend heading downward. To do this, we must acknowledge the violent streak in everyone, use cultural norms to push it into the corner, and then vigilantly stand guard to keep it away the center of our lives.

Alas, we live in a free country. Weapons of mass destruction can be legally bought and sold. Moral deterrents based on religion cannot play a role in public policy. Prostitution, gambling and drugs are heavily regulated, but military arms are not. This leaves the door open to those who would profit by selling gratuitous violence to the primitive parts of our brain.

The door has stayed open because the link between exposure to violence and violent behavior is complex and open to question. "We need to know more," say the critics of gun control, " before the evidence justifies action." Meanwhile, the body count rises.

Intermission.

I now ask that you set aside any background or expertise associated with my byline to the lower right. Think of these words as having been written by the person beneath the columnist's persona, the one whose photo is to the upper left. The warm and fuzzy father whose heart is broken for the unnecessary losses of others. The father who's thankful that his kids are now beyond public school.

That personal side of me asserts that the 1, 2 and 3 behind the massacre are: 1) our gun-soaked visual culture; 2) our inadequate delivery of mental health services; and 3) our lax regulations of weapons. Of these three, the last is easiest to fix because it's self-evident, tangible, inexpensive and requires nothing more than a Congress with backbone. I suggest a ceremony in Washington, D.C. where the nation's private arsenal of military weaponry — gathered by our elected representatives from their districts — is melted down to an indelible monument for domestic peace.

Next in line is the mental health delivery system, about which I've got plenty of personal experience, not yet shared in this column. It's crazy how we stigmatize mental health relative to physical health, simply because it's less visible and therefore harder to grasp. Our personal identities, egos, greatest joys, and even our souls are, in fact, mental phenomena supported by other bodily tissues. "Cogito ergo sum."

Last and most insidious is our violence-prone popular culture. Though hard to define, it's easy to see. Consider the entertainment of the 1930s as manifested by the classic movies of that era. Cigarettes are a pervasive presence, women are dolls, and practically all the violence is either off-screen or minimized. Today in the 2010s, the situation is reversed. Violence is often the main draw, women are women, and smoking is marginalized.

The humans who watched the 1930s and 1910s films as young people — my parents and my adult children — are the same. What's changed is the culture. Progress has been made on two of those fronts. We've lost ground on the third. Let's take it back.

Peace be with you.

Robert M. Thorson is a professor of geology at the University of Connecticut's College of Liberal Arts and Sciences. His column appears every other Thursday. He can be reached at profthorson@yahoo.com.